1. Field of the Invention
The present invention relates to a semiconductor device and a method for manufacturing the same.
2. Background Art
HfSiON is considered to be promising in regard to leak current, dielectric constant, thermal stability, etc., as a gate insulation film material to replace SiO2. Also, metal gate electrodes are favorable to improve transistor performance.
However, in the case where, for example, TiN is used as a gate electrode in a structure in which HfSiON is used as a gate insulation film, Hf in the HfSiON film undesirably diffuses into the TiN film due to heating during manufacturing steps, causing an undesirable increase of leak current and deterioration of reliability of the gate insulation film.
Although gate electrodes of HfSi and HfC formed as films by sputtering are reported by T. Hirano et al., IEDM 2005, 911 and by W. S. Hwang et al., VLSI 2007, 156, respectively, concerns remain in regard to film-quality defects due to sputter damage.